Mutations in LOXHD1, an Evolutionarily Conserved Stereociliary Protein, Disrupt Hair Cell Function in Mice and Cause Progressive Hearing Loss in Humans
Nicolas Grillet1, 11, Martin Schwander1, 11, Michael S. Hildebrand2, Anna Sczaniecka1, Anand Kolatkar1, Janice Velasco3, Jennifer A. Webster4, Kimia Kahrizi5, Hossein Najmabadi5, William J. Kimberling6, Dietrich Stephan3, 7, 8, Melanie Bahlo9, Tim Wiltshire10, Lisa M. Tarantino10, Peter Kuhn1, Richard J.H. Smith2 and Ulrich Müller1,
1 Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
2 Department of Otolaryngology Head and Neck Surgery, University of Iowa City, IA 55242, USA
3 Genome Institute of the Novartis Research Foundation, San Diego, CA 92121, USA
4 Neurogenomics Division, Translational Genomics Research Institute, Phoenix, AZ 85004, USA
5 Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
6 Department of Genetics, Boys Town National Research Hospital, Omaha, NE 68131, USA
7 Arizona Alzheimer's Consortium, Phoenix, AZ 85004, USA
8 Banner Alzheimer's Institute, Phoenix, AZ 85004, USA
9 Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Parkville 3052 VIC, Australia
10 Department of Psychiatry, University of North Carolina, Chapel Hill, NC 27516, USA
Abstract
Hearing loss is the most common form of sensory impairment in humans and is frequently progressive in nature. Here we link a previously uncharacterized gene to hearing impairment in mice and humans. We show that hearing loss in the ethylnitrosourea (ENU)-induced samba mouse line is caused by a mutation in Loxhd1. LOXHD1 consists entirely of PLAT (polycystin/lipoxygenase/ -toxin) domains and is expressed along the membrane of mature hair cell stereocilia. Stereociliary development is unaffected in samba mice, but hair cell function is perturbed and hair cells eventually degenerate. Based on the studies in mice, we screened DNA from human families segregating deafness and identified a mutation in LOXHD1, which causes DFNB77, a progressive form of autosomal-recessive nonsyndromic hearing loss (ARNSHL). LOXHD1, MYO3a, and PJVK are the only human genes to date linked to progressive ARNSHL. These three genes are required for hair cell function, suggesting that age-dependent hair cell failure is a common mechanism for progressive ARNSHL.